IDoc '&': Control record exists already

What causes this issue?

During reloading of IDoc number &v1& to the database, it was discovered
that a control record with the given number already exists in the
database (program &v2&, routine &v3&).

System Response

The IDoc could not be reloaded successfully.

How to fix this error?

Please check if the data you wish to reload is already available in the
database.

Error message extract from SAP system. Copyright SAP SE.